After distant metastases have occurred, treatment options that physicians may consider include:
- Surgery is preferred if the physician assesses that surgical resection is possible;
- Radioactive iodine (RAI) therapy may be attempted if the metastatic lesion is capable of iodine uptake;
- External radiation therapy;
- If the tumor is not progressing or is progressing slowly, is asymptomatic, and is not invading important areas (such as the brain and spinal cord), the physician may also recommend close follow-up with endocrine therapy (taking thyroxine tablets);
- For refractory differentiated thyroid cancer with rapidly progressive disease (cancerous tissue that does not take up iodine), chemotherapy and new targeted therapies may be tried.
Differentiated carcinoma (including papillary and follicular carcinoma)
The principles of treatment differ depending on the site of metastasis.
- Pulmonary metastases. The main focus of treatment is RAI. RAI therapy can be done every 6 to 12 months as long as the metastases have been able to take up iodine.
- Bone metastases.
- Bone metastases. Bone metastases can be treated with RAI if the metastases have a high iodine uptake capacity. However, in most cases, RAI is not effective in treating bone metastases. If the bone metastasis is solitary, your doctor may treat it with surgical resection plus RAI, which can relieve bone pain and possibly eliminate the bone metastasis.
- Brain metastases. In the case of oligometastases (few lesions), a method such as “Gamma Knife” may be used to remove the lesions that are causing clinical symptoms. Gamma Knife is a precision radiotherapy technique that uses gamma rays produced by cobalt-60 to deliver a single, high-dose focused irradiation to the lesion, like a “radiographic knife”. Because of the “blood-brain barrier,” targeted drugs and RAI therapy are not effective for intracranial metastases.
RAI therapy can only be done after total/near-total thyroidectomy, so if distant metastases are found at the initial diagnosis, total thyroidectomy and subsequent RAI therapy can be done.
Medullary and undifferentiated carcinoma
Medullary and undifferentiated cancers do not have iodine uptake and RAI therapy is not effective. Doctors may try local external radiation therapy, or systemic chemotherapy or targeted drug therapy.
What factors affect outcomes?
What factors affect the outcome?
After the development of distant metastases, the outcome of treatment is influenced by a number of factors. This includes the patient’s age, the type and characteristics of the pathology of the primary site, the number, size, and distribution of metastases (lung, bone, brain), and the response of the metastases to treatment.
Overall, patients with thyroid cancer have better outcomes, especially with differentiated thyroid cancer, and often have ways to cope and achieve long-term survival, even if distant metastases occur.
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Co-written by Dr. Tingting Zhang, Cancer Hospital of Fudan University